El Niño and La Niña

The short story:

El Niño

The cyclical warming of sea surface temperatures off the western coast of South America that can result in significant changes in climate in the tropical Pacific Ocean and elsewhere around the earth. El Niño is strongly related to changes in pressure patterns and wind patterns around the tropical Pacific Ocean.

La Niña

The cyclical cooling of sea surface temperatures off the western coast of South America that can result in significant changes in climate in the tropical Pacific Ocean and elsewhere around the earth. La Niña is strongly related to changes in pressure patterns and wind patterns around the tropical Pacific Ocean.

Clouds

Cloud-seeding

Cloud seeding is a way of changing clouds by adding other substances to them. It has been done sometimes to try and make clouds produce more rain. Chemicals are added (as a very diffuse smoke of ultra tiny particles) to try and make the tiny cloud water droplets grow bigger so they start to fall, collide with other droplets and grow to raindrops. Sometimes instead of adding chemicals, very cold air is spread in the cloud so the droplets freeze, as this has the same effect. Cloud seeding has also been done to try and make hailstorms produce less hail: the method is the same as for producing more rain. The idea is that by making lots and lots more raindrops (or in this case they are frozen, so hailstones) none of them get to grow big enough to fall and damage crops and buildings. So far we do not know enough about clouds and how to seed them, to be sure of the effects. We might make less rain when we want more, or more hail when we want less. So cloud seeding is not done in New Zealand.

Links to other websites

Wind chill factor

The wind chill factor combines the temperature and wind speed to tell you how cold the wind makes it "feel". It gives a very rough idea of potential risks caused by the combination of cold and wind when outdoors. The links below give information on how the wind chill factor is calculated.

Ideas for projects using climate data

Climate data for projects

These include rainfall, air and earth temperatures, frost, wind, humidity and a summary of climate extremes.

Reefton climate data

Raw data from the Reefton Climate Station are available at no charge. These can be used in statistical assignments. The record is from 1960 to date for rainfall, maximum, minimum and grass minimum temperatures. Other available elements have shorter records. These records can be accessed through the CliFlo screen. The agent number for Reefton is already in place. The data type should be selected first, and then the dates. Not all data types are available from Reefton.